The harmony of the physical body development of human beings and working constantly since antiquity, became part of the educational ideal in Greece (KALOSKAGATHON - Nice man and good) or the Roman baths. (Mens sana in corpore sano - Juvenal). In this study we aimed to accomplish finding harmonious physical development of students in preparatory class at Secondary School No. 16 in Bucharest. Objectives of the study is to determine the factors that influence the physical, cognitive and psycho social development of 6-7 years pupils. The methods used in this study are: the literature, teaching observation, measurement method, statistical and mathematical methods of data processing and interpretation. Observations and measurements carried out proves that the psychological and physical development of students are below the required values corresponding to their age which shows lack of physical activity practice by not participating actively in physical education lessons and the lack of games and recreational activities in free time. In a study conducted we have concluded that the introduction of three hours of physical education, as required by law, it is imperative that all pupils benefit from a harmonious physical development. Moreover families and schools are responsible for pupils' participation in physical activity, especially in the form of age-specific play.